Blindstitch attachment for sewing machines



Aug. 24; 1954 A. MOSBERG 2,587,193

BLINDSTITCH ATTACHMENT FOR SEWING MACHINES Filed New. 18, 1952 2 Sheets-Sheet 1 AWnG/VE) Aug. 24, 1954 A. MOSBERG BLINDSTITCH ATTACHMENT FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed Nov. 18, 1952 Patented Aug. 24, 1954 BLINDSTITCH ATTACHMENT FOR SEWING MACHINES Abraham Mosberg, New York, N. Y. Application November 18, 1952, Serial No. 321,091

4 Claims.

The principal object of this invention is to provide a novel and improved sewing machine attachment of the character and for the purpose mentioned, which is reasonably cheap to manufacture, easy to attach, detach and use, and which is efficient in carrying out the. function for which it is designed. Other objects and advantages will become apparent as this disclosure proceeds.

Essentially, I remove the presser foot and the straight needle of an ordinary sewing machine and provide an attachment having a frame which is detachably securable onto the presser foot bar of the sewing machine and presents a portion which serves as the presser foot. This frame carries a curved needle on a swingable arm, a looper associated with means which when actuated, will impart to such looper its required movements, and a member detachably securable to the machines needle bar and movably mounted on said frame; such last mentioned member, upon up and down movement of the machines needle bar, being adapted to operate the curved needle and the looper mechanism. The design is such that the curved needle and the looper operate in proper timed relation.

In the accompanying drawings forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

Fig. l is a perspective view of a sewing machine attachment embodying the teachings of this invention and is shown in use position on a sewing machine. In the condition here illustrated, the curved needle is at the end of its sewing stroke, ready to return to normal rest position which will occur when the machines needle bar which is here in its raised position, moves downward.

Fig. 2 is a diagrammatic view showing the relative positions of the attachments components when its curved needle has returned to normal rest position.

Fig. 3 is a fragmentary section taken at lines 3-3' in Fig. 1. The machines needle bar and the attachments member which is carried by such needle bar, are indicated by dash and dot lines for they are really no part of the mentioned section, but are included to indicate their position in relation to the components of said section.

Fig. 4 is a perspective view of a component of my attachment shown in Fig. 1.

Fig. 5 is an enlarged fragmentary section taken at lines 5-5 in Fig. 4.

Fig. 6, is an enlarged diagrammatic view showing the position of the needle with respect to com.- ponents shown in Fig. 5.

In the drawings illustrating a preferred emsegmental gear 42 at all times.

bodiment of this invention, the numeral I 5 designates generally a frame which by the screw i6, is adapted to be detachably mounted onto the presser foot bar ll of an ordinary sewing machine it whose presser foot and needle have been removed. Said frame [5 extends forwardly of the machines needle bar Hi. When the presserfoot bar ll is let down, the undersurface 20 of the rear part of the frame, serves as a presser foot cooperating with the machines cloth-feeder teeth 2! to advance the work when the machine is running. The undersurface 22 of the front part of said frame, is clear of the work-resting plate 23, which latter is detachably mounted on the machine table, extends a bit behind the plane of the front wall 24 of the frame and to some distance in front of the frame, and of course, all below said frame; Extending forwardly of the frame l5, are the presser foot fingers Z5 and 26, whose forward tips 25, 26' are upturned slightly to admit the work between them and the plate 23. The finger 25 is bowed at 25", whereon the curved needle 2i in its swinging movement slides. Through a central slot 23 in plate 23, extends the exposed upper portion of a disc 29 which is rotatably mounted as shown in Fig. 5 on the axis pin 38 which passes through bracket pieces 3| secured on the underside of the raised plate member 23. Said plate may have the slotted lug 32 to facilitate its at tachment by screw means not shown, onto the machines table surface. A torsion spring-loaded axis pin 33,extends in parallel relation to the pin 30, from the spring-holding casing 34 on the finger 26. This pin 33 terminates in an inverted V-shaped metal piece 35 urged against the periphery of the small disc or Wheel 29. Said piece 35 may be deemed an inverted crotch which cooperates with said wheel 29 to form an upward bend in the cloth as the latter passes between them. Said wheel is a bit behind the crotch. Near its bottom, the frame [5 carries a cylindrical member 36 on a horizontally fixed pin 31. Said member 35 is free to swing about and slide along said pin 31. This pin extends from in front of the position of the needle bar id to in front of the front wall 24 of the frame l5. Said member 35 may fit in a cylindrical bore 33 in the frame body. The forward portion of said member 3t is a comparatively wide-faced gear 39, and its rearward portion is a barrel cam whose groove or track is engaged by a follower ll fixed to the frame. At least a part of said gear 39 is outward of the bore and in engagement with the Said gear E2 is mounted for rotation on axis 43, and has a suitably bent arm M, at whose free terminal 45, the curved needle 21 is mounted by means of the set screw 46. The frame l includes an upright channel element 46 which serves as a track for the rack member 41. The numeral 43 denotes the rack teeth which are in engagement with the gear l2, but clear the gear 39. The member 41 is mounted for up and down sliding movement on the frame [5, and is adapted to be secured detachably to the needle bar H), by being provided for instance with a clevis 49 to be engaged by the tightening screw 5!]. Said member 47. is held in assembly with the frame l5, by the screw 5| whose shank extends through and is free to slide along the vertical slot 52 in the frame. When the rack member 41 is in raised position as in Fig. l, the needle 21 is through the work 53 and at the end of its stitching stroke. When said rack member is in its lowered position as in Fig. 2, the needle 2'! is at normal rest position.

A looper pin or arm 54 extends forwardly from the face of the gear 39. Such looper is provided with any suitable tip 55 to cooperate with the needle 2i to accomplish the required sewing as is well known in the art. Such tip is of course off the center of said gear 39. In the gear system illustrated, for each complete uni-directional movement of the needle bar IS, the gear it makes about a one-quarter turn and the gear 39 makes such part of a turn that the looper 54 at its terminal positions as shown in Figs. 1 and 2 respectively, is at the terminal position the needle 27' is then at, and that during each such uni-directional movement of the gear 39, the locus of movement of the looper tip shall pass above the axis pin 31. It is also required, that between each such start and finish of each uni-directional rotation of the gear 39, the looper 54 shall move longitudinally, first away, then towards the plane of the needle 21. It is evident that the barrel cam on the member 36, will Cause said member to retract into and then withdraw from the chamber 38, during each complete uni-directional rotary movement of said member on its axis pin 3'1.

It is to be noted that it is preferred, that the vertex of the crotch 35, the plane of the Wheel 29, the axis of the pin 31 and the axis of the needle bar position 19, be coplanar. Such common plane will of course be a vertical one, perpendicular to the plane of movement and position of the needle 2i.

To mount or remove the attachment, only the manipulation of the screws I6, 50 and the one holding the plate 23 at slot 23' is necessary. Upon removal of the attachment, the machine is restored to its normal use condition by mounting its straight needle in the needle rod [9, and its p-resser foot is mounted onto the bar ill.

To sew, with the attachment as shown in Fig. l, the operator first raises the handle 5?, thus lifting the frame l5 and all it carries. He then places the work on the plate 23 and on the periphery of the wheel 29, so that the proposed line of stitching be in the plane of said wheel presuming such line to be straight. He then releases the handle 5?, whereupon the fingers 25 and 26 are atop the Work 53, and the crotch member in cooperation with the wheel 29 form an upward bend in the work where the latter is between said crotch and Wheel. He now operates the machine l8 and feeds the work rearwardly at such rate as is accomplished by the feeder 2i until there is sufficient material of the work to get it engaged by the feeder teeth 2 I. It, is to be noted that the plane of the needle is immediately behind the crotch piece 35 and the needle slightly touches the periphery of the wheel 29 during needle swing. The mentioned preliminary hand feed of the work until it reaches the feeder 2 I, is avoided when the stitching is to be along the endless hem as of a skirt. In such instance, the work is initially set below the frame and over the feeder teeth 2|, so that all feeding of the work i accomplished by such feeder teeth.

Since the required movements of the needle 2'! and its associated looper 51!, are present, the accomplishment of the sewing of a single thread, chain-stitch, blind-stitch is evident to those versed in this art, and therefore needs no further explanation.

This invention is capable of numerous forms and various applications without departing from the essential features herein disclosed. It is therefore intended and desired that the embodiment shown herein shall be deemed illustrative and not restrictive and that the patent shall cover all patentable novelty herein set forth; reference being had to the following claims rather than to the specific description herein to indicate the scope of this invention.

I claim:

l. A single thread, chain-stitch, blind-stitch attachment for a sewing machine, comprising a frame adapted to be secured onto the presser foot bar of a sewing machine whose needle has been removed, a vertically positioned rack adapted to be mounted on the needle bar of said machine, a first member swingably mounted on the frame, a curved needle with a hole therethrough at its point for a thread; said needle extending from said first member and positioned thereon whereby upon movement of said first member the needle will move in its own plane which is vertical and forward of the frame, a second member positioned behind said plane, swingably mounted on the frame and slidable along its own axis of swing; the line of said axis, intersecting said plane, a looper member carried on said second member, extending therefrom forwardly towards said plane; the tip of said looper member being spaced from the axis of swing of said second swingable member, a first means on the frame to reciprocate the second swingable member along the axis of the latter during a predetermined partial turn of said second member; said first means being operated by any of mentioned members and gears on the frame, associated with said first and second members in engagement with each other and at least one of said gears being in engagement with said rack and operated thereby, whereupon movement of the said rack carried by the needle bar, said first and second members will be simultaneously swung predetermined parts of a turn respectively and the said second member will be automatically slid along its axis of swing; the sliding movement of said second member along its said axis being such that when the needle is at the terminal positions of its travel, the looper tip will be at needle point region and when the needle is between its said terminal positions, the looper tip will be spaced from and to one side the plane of the needle.

2. The attachment as defined in claim 1, wherein the rack is slidably mounted and permanently associated with the frame and wherein the gears are one on each of the first and second swingable members.

3. The attachment as defined in claim 2,,wherein the gears associated with the first and second members are in direct engagement.

4. In combination with a sewing machine, a single thread, chain-stitch, blind-stitch attachment comprising a frame adapted to be secured onto the presser foot bar of said sewing machine whose needle has been removed, a member adapted to be mounted on the needle bar of said machine, a first member swingably mounted on the frame, a curved needle with a hole therethrough at its point for a thread; said needle extending from said first member and positioned thereon whereby upon movement of said first member the needle will move in its own plane which is vertical and forward of the frame, a second member positioned behind said plane, swingably on the frame and slidable along its own axis of swing; the line of said axis, intersecting said plane, a looper member carried on said second member, extending therefrom forwardly towards said plane; the tip of said looper member being spaced from the axis of swing of said second swingable member, a first means on the frame to reciprocate the second swingable member along the axis of the latter during a predetermined partial turn of said second member; said first means being operated by any of the mentioned members, a second means on the frame, associated with said first and second members and operated by the member associated with the needle bar whereupon movement of said member carried by the needle bar, said first and second members will be simultaneously swung predetermined parts of a turn respectively and the said second member will be automatically slid along its axis of swing; the sliding movement of said second member along its said axis being such that when the needle is at the terminal positions of its travel, the looper tip will be at needle point region and when the needle is between its said terminal positions, the looper tip will be spaced from and to one side the plane of the needle, presser foot fingers extending forwardly from the frame and means to form an upwardly extending bend in material to be stitched, comprising a plate member adapted to be mounted on the table of the sewing machine beneath said fingers, a disc rotatably mounted on said plate on an axis parallel to the plane of the needle along the horizontal and a spring-pressed inverted crotch mounted on one of said fingers and acting downwardly on the disc; the needle in its movement, contacting the periphery of the disc behind the crotch.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,618,232 Mikolas Nov. 18, 1952 FOREIGN PATENTS Number Country Date 665,080 Germany Sept. 16, 1938 

